At present, the IP address has dual functions in TCP/IP (Transmission Control Protocol/Internet Protocol) widely used in the Internet, i.e., the IP address serves not only as the location identifier of the communication terminal host network interface of the network layer in the network topology, but also as the access identifier of the host network interface of the transmission layer. The case of host mobility was not taken into consideration when the TCP/IP protocol was initially designed. However, as host mobility becomes more and more popular, the defect of semantics overload of this kind of IP address becomes more and more apparent. When the IP address of a host changes, not only the route but also the access identifier of the communication terminal host will change, resulting in bigger and bigger load of the route. The change of the host identifier will cause interruption of application and connection.
The access identifier and location identifier separation is proposed to aim at solving the problems of semantics overload of the IP address, severe load of the route, security and so on, separating the dual functions of the IP address, realizing support for problems including mobility, multi-homeness, dynamic redistribution of IP addresses, reduction of route load, and inter-visit between different network areas in the next generation of internet.
After a user signs a service agreement with a network B, if the user roams to an area uncovered by the network B (a roaming area), the user cannot be served by the network B, but if the roaming area is an area covered by a network A and network A has signed a roaming agreement with network B, and the user is allowed to roam, then the user can still enjoy the same service in the area covered by network A. However, currently there is still no method for providing services for a roaming user in the network of identity identifier and location identifier separation.